I recently came across this treatment and wonder if anyone has any experience---good or bad---with it. I am told it is called 'mercy.'
Responses to 2nt opening bid and to 2n after 2c opening bid
normal puppet, stayman, texas and delayed texas.
transfer to hearts–3d—followed by 3s shows hand with 5 hearts and without 4 spades, while rebid of 3n after 3d shows hand with 5 hearts and 4 spades.
2n-3n shows hand with 5 spades and 4 hearts.
2n-4s is relay to 5c and responder either has hand that plays best in 5c or 5d.
2n-4c directly is gerber–min-max and 2n-4n is quantitative. If q, opener can end auction, pass. the buck with 5n or give RKC response to help partner decide.
If none of those patterns apply and as responder you want to end at 3n or if you have hand with minors, then—
3s is relay to 3n. After relay,
4c or 4d sets trump and asks for RKC response from opener.
4h shows slamish hand with length in both minors, ask opener to select minor by step response, to which responder gives RKC response.
4s shows length in both minors, game only, opener selects game.
Plus... it's free!